After you've gotten to a certain stage, where the bitterness has subsided and brews are lasting over a minute or three (10-15 or more brews) you can put cool water over the leaves and rest them overnight. Drink that water in the morning and put hot water over for 5 minutes, drink, put cool water over, go to work. Come home, drink, add hot water, cool water, sleep, drink, repeat, drunk!

I personally because I hate to boil water specifically for one or two infusions of a tea, after I get a day or two completely out of the tea, I move onto just cold water extended length steeps. Although if I do happen to be making some other tea at the time I will hit the leaves with hot water.

With very old pu'er, you can also do long infusions in a thermos, or even boil the tea leaves once the tea stops producing drinkable tea via the normal methods.

I have mixed feelings about this. With very old and rare tea, I don't like letting any bit of it go to waste. At the same time, there is something to be said for remembering at tea when it was at its peak.